The present invention relates to an information reproduction system which can prevent code reproduction errors and reduces decoding processing of invalid block data. This is accomplished by adaptively controlling the block decoding method in accordance with the image sensing state of a code upon reproduction of a code which is obtained by optically readably recording a plurality of blocks having block data each of which is obtained by segmenting information data in units of predetermined information volumes, and block headers indicating addresses assigned in units of blocks, in accordance with a predetermined block layout format.
The assignee of the present application who is also the assignee of U.S. patent application Ser. No. 08/571,776 which relates to an information recording medium and information reproduction system as a system that segments digital data in units of blocks each having a predetermined information volume, records the segmented blocks, and reproduces the recorded blocks.
This system reads the segmented block data together with their address data, and reproduces information by coupling the block data on the basis of the address data.
Since this system has a mechanism for recording/reproducing data in units of segmented blocks, it has excellent expandability of data and reading flexibility, and can read data that cannot fall within one image sensing frame by scanning a code.
This system is excellent since it also allows reading based on manual scans that may cause blur or changes in scan speed.
The system is very effective for recording/reproducing data in units of segmented blocks.
Hence, since the system decodes data in units of blocks, invalid blocks or inappropriately sensed blocks must be decoded carefully.
As the measure against such blocks, U.S. Ser. No. 08/571,776 (identified above) proposed the following systems. That is, in one system, data are decoded in turn from blocks on the image sensing frame on the scan direction side, and decoding is stopped upon detecting block data with identical address data. In the other system, data are decoded in turn from outer blocks on the image sensing frame, inner block data on the image sensing frame are overwritten on the decoded data, and block data which are expected to suffer less distortion on the inner side of the image sensing frame are finally reproduced.
With these systems, high-speed decoding can be attained by obviating the need for decoding invalid blocks, and code reproduction errors due to defective readout blocks can be reduced.
However, the system disclosed in U.S. Ser. No. 08/571,776 does not sufficiently consider the image sensing state of a code.
For example, in the system disclosed in U.S. Ser. No. 08/571,776, even when illumination on the scan direction side is dark due to scanner tilt, and the image sensing state is inappropriate, block data on the scan direction side are preferentially decoded, resulting in code reproduction errors.
Also, in the system disclosed in U.S. Ser. No. 08/571,776, since the image sensing states of blocks change as scanning progresses, blocks sensed at the center of the image sensing frame are not always the optimal ones.
In other words, the system disclosed in U.S. Ser. No. 08/571,776 does not appropriately decode data in correspondence with the image sensing state of the code, and leaves room for improvement in this point.